C-cyclohexyl-diphenylamines and process for making them



Patented Mar. 19, 1940 V'UN'ITED STAT S omen C-CYGLOHEXiiL-DIPHENYLAIVIINES PRQCESS FOR MAKING THEM Frank B. Smith and Harold Moll, Midland,

Mich., assignors' to The Dow Chemical Company, Midland,

gan

Mich., a corporation of Michi- No Drawing. Application May :2, 1938, Serial N0."205 ,527

7 Claims.

This invention concerns certain new chemical products, namely diphenylamines substituted in either or both of the benzene nuclei by one or more cyclohexyl groups, as well as mixtures com- (ci. zoo -51c) perature is usually between about 150 and 250 (3., although somewhat higher temperatures may be employed if desired. The reaction is usually complete in' from 4 to 30 hours, but a longer -5 prising such compounds. These compounds and period may sometimes be required. After com-- 5 their mixtures vary in physical properties from pletion of the reaction, the catalyst is removed high-boiling, viscous liquids to crystalline solids. and the reaction mixture is distilled under vac- They are substantially insoluble in water but are uum to obtain the cyclohexylated diphenylamine I soluble in a number of organic solvents such as product which is usually a mixture of monoand l 1 acetone, carbon tetrachloride, toluene, etc. They poly-cyciohexyl-substituted diphenylamines. 1'0 may be employed as plasticizing agents for cel- The distilled product is ordinarily employed lulose derivative, e; g. ethyl cellulose, cellulose directly as a plasticizing agent, dye-stuif interacetate, etc., compositions and are also useful mediate, etc., without further purification. If as rubber antioxidants and as intermediates in desired, however, it may be fractionally distilled the preparation of other products such as dyeinto fractions representing isomeric mono-sub- 18 stuffs, pharmaceuticals, etc. stituted diphenylamines, di substituted di The new cyclohexyl-diphenylamines are prefphenyl s. Also, such isomeric erably prepared by reacting diphenylamine with tures may be further fractionated to obtain the .cyclohexene in the presence of an acid-activated individual compounds contained therein, e. g.-

2 bleaching earth, such as Retrol, Tonsil, etc. 4-cyclohexyl-diphenylamine, 4.4 dicyclohexyl- 80 If desired, however, other cyclohexylating agents, diphenylamine, etc. e. g. cyclohexyl chloride, cyclohexyl bromide, The following examples will illustrate several etc., may be employed. The reactants may be ways in which the principle of our invention employed in any desired proportions depending has been applied but are not to be construed as upon the products desired. For example, a limiting the same:-

molecular excess of diphenylamine may be re- Example 1 acted with cyclohexene to produce a liquid mixture comprising 'unreacted diphenylamine, a A m e of 507 grams DD Y relatively large amount of mono-cyclohexyl-dimols) of a technical grade of diphenylamine and phenylamine, and small amounts of di-cyclo- 10 grams of Retrol was placed in a flask fitted hexyland poly-cyclohexyl-diphenylamines. A with a reflux condens Water Separator, therlarger yield of the poly-substituted compounds mometer, an stirrer. n W h e at a mmay be obtained by decreasing the proportion of perature of approximately 200 C. until all of the diphenylamine employed or byreacting cycloe residual water contained in the Retrol had been hexane with the monoand di-substituted comdriven off. 541 grams (6.6 mols) of cyclohexene 35 pounds obtained from a previous reaction. Ordiwas then added gradually with stirring over a narily, we prefer to employ approximately 1-3 period of 100 hours. During the initial part of mols of cyclohexene per mol of diphenylamine. the addition, considerable heat was evolved from The amount of catalyst varies with the particuthe reaction and the temperature rose to 250 C.

lar reactants employed and the conditions under Upon completion of the reaction, the mixture 40 which the reaction is carried out, but we usually was cooled to 150 C. and filtered while hot to reemploy between 0.02 and 0.10 part by weight of move the catalyst. The crude product thus obcatalyst per part of diphenylamine. tained was a dark red viscous liquid. It was The reaction is conveniently carried out by 'fractionally distilled under vacuum to obtain the adding the cyclohexene to a heated mixture of following fractions: 45

Table Fraction No 1 2 3 4 5 Product Unreacted di-phon- Intermediate itac- Mono-cyclohexyldi- Di-cyclohexyl di- Poly-cyclohexyl di- 50 ylamine. tion. phenylamines. phenylamines. phenylamines. Appearance WhiIte crystalline Light yellow liquid Yi i l lg vg crystalline Ygl lgw viscous liq- Redviscous liquid. Boiling range wife '20o o. at20 200 -250 0. at 20 25o-27h c. at 20 270-o0 0. at 20 Above 300 0. at 20 mm. mm. mm. mm. mm. Melting point 49-50 O- 32-34 G- Bpeciflcgravity 80l80 O. 1.043.- 1.034 55 Refractive index 1.6109 at 25 o 1.5925 at 35 0 diphenylamine and the catalyst, and thereafter Example 2 I heating and stirring the reaction mixture until A mixture of 169 grams (1.0 mol) of purified the condensationis complete. The reaction teni-' diphenylamine and 10 grams of Retrol was heated at 200 C. as in Example 1 until the residual water had been removed from the Retrol. 181 grams (2.2 mols) of cyclohexene was then added gradually with stirring over a period of four hours during which time the temperature was maintained at approximately 200 C. Upon completion of the reaction, the Retrol was filtered 01? and the product obtained as a dark red viscous liquid. It was fractionally distilled under vacuum to give fractions corresponding to those obtained in Example 1.

In the following claims, the expression C-cyclohexylated diphenylamine refers to diphenylamine in which at least one nuclear hydrogen atom thereof has been substituted by the cyclohexyl group.

Other modes of applying the principle of our invention may be employed instead of those explained, change being made as regards the method herein disclosed or the materials employed, provided the method stated by any of the following claims be employed or the product claimed in any of the following claims be obtained.

We therefore particularly point out and distinctly claim as our invention:

1. C-cyclohexylated diphenylamine.

2. A mixture of monoand poly-C-cyclohexylated diphenylamine.

3. A mixture consisting of isomeric mono-C- cyclohcxyl-diphenylamines, said mixture being a yellow crystalline mass having a melting point of approximately 32-34 0., and distilling between 250 and 270 C. under 20 millimeters pressure.

4. A mixture consisting of isomeric di-C-cyclohexyl-diphenylamines, said mixture being a yellow viscous liquid distilling between 270 and 300 C. under 20 millimeters pressure, and having a specific gravity of approximately 1.03 at /80 C.

5. A method for the preparation of C-cyclohexylated diphenylamines which comprises heating a mixture of diphenylamine and cyclohexene to a reaction temperature below that at which decomposition of the mixture takes place and in the presence of an acid-activated bleaching earth.

6. A method for the preparation of C-cyclohexylated-diphenylamines which comprises heating a mixture of diphenylamine and cyclohexene to a temperature between about and about 250 C. in the presence of an acid-activated bleaching earth.

'7. A method for the preparation of a mixture of C-cyclohexylated-diphenylamines which comprises heating diphenylamine with from about 1 to about 3 molecular equivalents of cyclohexene at a temperature between about 150 C. and about 250 C. in the presence of an acid-activated bleaching earth.

FRANK B. SMITH. HAROLD W. MOLL. 

